HU222528B1 - Process for forming items having layers with controlled thickness - Google Patents

Abstract

The present invention relates to a process for the production of industrially produced articles, such as leather imitations or the like, from thermoplastics, thermosetting materials or elastomers, having at least one foamed layer, characterized by the steps of: a) forming a single layer of material in a mold forming a top (visible) layer of the finished product, b) forming a second layer of foamable material on a first layer called in a further tool casting step, c) completing the solidification of said layers and the foaming of said second layer at elevated temperatures, said foamed layer being predetermined in order to ensure the thickness and shape of the material thus formed, a backsheet (7) made of a brittle material is contacted, the thickness and shape of said foamed layer being formed by a counter-tool (8) or a backsheet (7) made of said brittle material. ŕ

Description

Molding of polystyrene, PVC powder or other thermoplastic thermosetting elastomeric materials by means of die casting is generally known. Briefly, this die casting process consists of filling the preheated metal die with a powder or liquid polymeric material, removing excess liquid or solid material, and then heating the die to complete gelling, melting, and / or curing the die material. The tool is then cooled and the molded body is removed from the tool.

The production of bi-colored or multi-colored leather imitation materials by die casting techniques is also known, for example, from EP 476,742 and WO 94/12331.

Particularly known in the automotive industry are articles which mimic perfectly the surface of natural leather and which are made in their final shape in a mold suitable for the design, using soft polyurethane foam, said polyurethane layer being placed between the leather imitation and a backsheet. Such a backsheet may be made of steel, thermoplastic or thermosetting resin, composite materials, or other materials.

The surface of the resulting object, in the case of objects in contact with the body or generally in the case of fixtures, is pleasant and soft to the touch. In addition, the foam layer dampens the impact of the finished product and consequently plays a safety role.

It is also well known to use calendering techniques to produce a soft, flat, foamed skin imitation, from which this imitation skin is thermoformed, and the use of adhesives is applied to the backsheet or pre-heat applied during the thermoforming operation. activated adhesive coated backing. In the latter case, the heat content of the thermoformed article is sufficient to effect this association. However, the finished products produced by this technique have portions with an inflated surface (including the foamed portion) which, as a result, tend to shrink, have lower abrasion resistance, less thickness, and are thinner at critical points.

The purpose of the tool casting technique is to obtain a soft skin imitation, especially for dashboard coatings and other body decoration elements, which does not adversely affect the thermoforming technique, i.e., does not cause the skin imbalance thickness, which causes frozen tension and higher temperatures cause.

It is an object of the present invention to provide dashboards, doors and other automotive decorations coated with imitation leather, which is produced by the so-called mold casting technique, which does not require foaming of the imitation leather with a suitable component with polyurethane. Such an operation is in fact costly and produces waste and requires special artificial leather mechanical strength and resistance, which increases the cost.

For this purpose, as well as other advantages, which will be apparent from the following description, the present invention proposes that articles such as imitations of leather or the like are made from thermoplastic materials, thermosetting plastics, or elastomers with at least one foam layer. with the following procedural steps:

a) forming a first layer of material in the die casting tool which forms the upper, i.e. visible, layer of the finished product,

b) forming a second layer of foaming material on said first layer in an additional die casting step,

c) solidifying said layers by gelling at elevated temperature and conveniently foaming said second layer to form a predetermined thickness and shape of said foamed layer, the resulting laminate being joined by a backsheet made of brittle material; the predetermined thickness and shape of the layer is provided by means of a counter-tool or the so-called rigid material backsheet.

Said thermoplastic, thermosetting or elastomeric materials can be selected from a wide variety of powder and liquid resins.

The second layer of said foaming agent is formed from a material which has been formulated with a blowing agent analogous to or compatible with this material, such as azodicarbonamide, sodium bicarbonate, citric acid or any other suitable agent.

Said first layer is produced in a single color or in two or more colors, for example by the process of the aforementioned European Patent Application EP 476,742 or WO 94/12331.

In the process of the present invention, the second layer, i.e. the foamed layer, is formed on the surface of the first layer which will be the invisible surface of the finished product.

In accordance with the object of the present invention, it is essential that the second layer of the foamable material

In step c), this layer is formed by foaming a predetermined, homogeneous, controlled-thickness foam, wherein the predetermined thickness is selected on a case-by-case basis to meet product requirements.

Consequently, the method of the present invention can provide a counter-tool having the shape of a reproduction of said hard material backsheet, so that said counter-tool can reproduce the shape of said backsheet on the surface of a second layer of foamed material, which is the reverse. As a result, such a surface is hollow and is the opposite of the backsheet surface that the design must accept.

A first embodiment of the method of the present invention using said counter-tool

According to EN 222 528 Β1, the procedure consists of the following consecutive steps:

a) forming a first layer of material in the die casting tool which forms the upper, i.e. visible, layer of the finished product,

b) shortly after step a), forming a second layer of foamable material on said first layer by an additional die casting step, b ') attaching said counter-tool to said tool,

c) terminating said layers by gelling and foaming said second layer at elevated temperatures, such as in a heating cabinet,

d) separating said tool and counter-tool,

e) cooling said tool,

f) removing the finished article (which is an imitation leather having a foamed layer having a foamed layer to counter-shape the backsheet),

g) joining the backsheet of the hard material with the resulting laminate by inserting said backsheet into a recess formed by said counter-tool on the opposite surface of the foamed layer using a suitable adhesive.

In another embodiment of the method described, after step b), the tool is placed in a heating cabinet for performing said step c), then removing said tool from the cabinet and connecting said counter-tool to said tool according to step b '). then cooling the tool and counter-tool, disassembling according to steps f) and g) above.

According to the process of the present invention, the counter-tool as defined above is required whenever the mold used for casting the tool, the plurality of materials, contains undercuts, or any problem occurs when removing the finished product from the tool.

However, if such a tool has no undercuts or no such problems, in another embodiment of the process of the present invention, said brittle material, which is to be combined with the skin to produce the finished product, can be used directly as a countermeasure.

In this case, said brittle backsheet can be directly associated with the laminate in the die and the whole object is removed from the die.

Therefore, in such a case, the method of carrying out the process of the present invention may comprise the following steps:

a) forming a first layer of material in the die casting tool which will form the upper, i.e. visible, layer of the finished product manufactured, a ') inserting said rigid material backsheet in said tool,

b) forming, on said first layer, a second layer of foamable material by a further step of molding such that said second layer substantially embeds said backsheet made of brittle material,

c) completing the consolidation at elevated temperature by gelling said layers and foaming said second layer,

d) cooling said tool and removing the finished product thus formed with the embedded rigid backsheet from the tool.

Alternatively, a different embodiment of the process of the present invention is possible, comprising the steps of:

a) forming a first layer of material in the die casting tool which will form the upper, i.e. visible, layer of the finished product,

b) further forming a second layer of foamable material on said first layer, b ') placing said second layer of said brittle material, suitably on its side facing said second layer with a suitable adhesive, e.g. hot-melt adhesive,

c) completing the solidification of said layers and the foaming of said second layer at elevated temperature, such as in a heating cabinet,

d) cooling said tool and removing the finished product thus formed with the embedded rigid backsheet from the tool.

According to a further embodiment of the present invention, in the most recently described process step, step c) can be performed first, and step b ') can then be performed.

For a better understanding of the features and advantages of the present invention, the following non-limiting examples are set forth and with reference to the accompanying drawings.

Each of these examples relates to one embodiment of the invention as defined above.

Figure 1 is a cross-sectional view of a tool according to the present invention when attached to a container containing polymeric material.

Figure 2 is a cross-sectional view when the tool container system is rotated 180 ° (i.e., upside down) to perform tool casting.

Figure 3 shows a cross-sectional view of the tool to which the first layer is adhered and the tool is returned to its initial position.

Figure 4 shows a similar cross-sectional view after the second operation of the tool filling and the foam material remaining adhered to the first layer.

Figure 5 is a schematic cross-sectional view of a tool / counter tool.

HU 222 528 Β1

Figure 6 is a cross-sectional view of the finished leather imitation article.

Figure 7 is a cross-sectional view of a leather imitation article to which the backsheet is glued.

With reference to Fig. 1, the symbol 1 denotes a container to be used for tool filling, to which a tool 2 is mounted in an operating position.

This tool is removed from a preheater cabinet or it can be heated with oil flowing in the gap between its inner and outer walls. After the tool is mounted on the container with a rotary axis 3 marked with a dashed line, the polymeric material 4, which may be a powder or liquid material, is brought into contact with the tool at 180 ° (or other appropriate rotation) as shown in FIG. 5A, and for the time required to adhere the desired amount of material to the hot tool.

After a further 180 ° rotation (or after another suitable rotation mode), the tool container is returned to its original position and will be as shown in Figure 3, where the first layer of composite leather imitation is indicated by 5. Immediately thereafter, the tool 2 is mounted on the tool container 1 containing the foamable material 9, rotated by 180 °, held upside down for the required time, and then rotated again by 180 ° to allow the liquid to drain. Eventually the situation will be what the

Figure 4 shows schematically, namely, a second foamed layer 6 is glued to the first layer of the composite leather imitation 5. Now, in order to provide the foamed layer 6 with a regular thickness and a homogeneous formation, a counter-tool 8 with a separating surface is used as shown in Figure 5.

The tool 2 carrying the counter tool 8 is now placed in a gelling cabinet (or the operator is waiting for the hot oil circulating to perform this operation) to complete melting of the material and foaming of the layer 6.

Once the casting and foaming step is completed, there are several alternative operations available depending on the manufacturer's preference:

- the tool and countermeasure can be disassociated to remove the manufactured leather imitation product from the tool after cooling the tool and then connect it to a backsheet 7 with a suitable adhesive-promoting system (primary treatment or hot-melt adhesive under pressure or other system);

- alternatively, as described above, it combines the laminated 5-6 skin imitations with the backsheet, utilizing the heat provided by the imitation leather and gelling after having previously treated said backsheet with a special hot-melt adhesive. The tool is then cooled and the finished object is removed from the tool and ready to be assembled, as shown schematically in Figure 6, showing the backsheet 7.

It has been stated above that the use of a counter-tool in the process of the present invention is particularly necessary if the tool has undercuts. Indeed, such undercuts would prevent the imitations of the skin into which the backside is embedded from being removed from the tool.

In such a case, said counter-tool may be provided with suitable retractable and extensible parts.

Thus, for example, a counter-tool comprising a plurality of rigid material inserts, each of which is independently adjustable and actuated by an actuator capable of extending portions of said counter-tool toward the opposite recessed wall of said undercuts will be suitable. or pull it in so that you can properly enter or exit them.

With regard to the description of the mechanical structure of such a counter-tool, reference is made, for example, to the above-mentioned International Patent Publication No. WO 94/12331.

Such a counter-tool may conveniently be provided with a release surface facing the surface of the foamed layer to which it is bonded.

The counter tool can then be properly thermostatized to continuously monitor the temperature conditions at which it operates.

The invention, which is essentially described above, can be utilized in a number of embodiments other than those described herein.

For example, one type of thermoplastic, thermosetting, or elastomeric material may be used for the outer, i.e., the first, skin layer, and the foamed, or second, layer of imitation leather.

In an alternative embodiment, the material used to form the first layer and the foam material used to form the second layer may be different materials.

The upper layer, i.e. the visible layer, as mentioned briefly above, can be formed in two or more colors, in which case the process described in EP 476,742 is used.

Claims (11)

PATENT CLAIMS A process for making articles made of at least one foamed layer, such as imitations of leather or the like, from thermoplastic materials, thermosetting materials or elastomers, comprising the steps of: a) forming a first layer of material in the mold for forming the upper, i.e. visible layer of the finished product, b) forming a second layer of foaming material on said first layer in an additional die casting step, c) at said elevated temperature, completing the consolidation of said layers by gelling and suitably foaming the second layer to form a predetermined thickness and shape of the foamed layer, The laminate thus formed is joined by a backsheet made of brittle material, while the predetermined thickness and shape of said foamed layer is provided by means of a counter-tool or said backsheet made of brittle material. Method according to claim 1, characterized in that the second layer of said foamable material is carried out by molding a die in said tool while controlling the thickness of said layer formed by foaming by a counter-tool whose contour reproduces the shape of said rigid material backsheet, so that the contour of said counter-tool is of a design opposite to said contour of the surface of said second foamed layer. The process according to claim 2, characterized in that it comprises the following steps: a) forming a first layer of material in the mold for forming the upper, i.e. visible layer of the finished product, b) forming a second layer of foamable material on said first layer in a further step of molding after step a), b ') sealing said counter-tool with said tool, c) completing the gelling of said layers at elevated temperature, such as a heat treatment cabinet, and foaming said second layer, which consequently takes the form of said counter-tool, d) disassembling said tool and counter-tool, preferably cooling the thermostatic counter-tool, e) cooling said tool, f) removing the manufactured object from the tool, g) joining said rigid material backsheet with the resulting laminate material, inserting said backsheet and, if necessary, gluing said foam layer into said recess formed by said counter-die. The process according to claim 2, characterized in that it comprises the following steps: a) forming a first layer of material in the mold for forming the upper, i.e. visible layer of the finished product, b) after step a), in a further tool casting step, forming a second foaming layer on said first layer, c) completing the gelling of said layers at elevated temperature, such as in a heat treatment cabinet, and foaming said second layer, c ') removing said tool from the heat treatment cabinet and mixing it with said counter-tool, d) cooling said tool and counter tool, e) disassembling said tool and counter-tool, f) removing the laminate from said tool, g) connecting said backsheet made of brittle material to the resulting laminate. The process of claim 1, further comprising the steps of: a) forming a first layer of material forming the upper layer of the finished product in the die casting tool, a ') inserting in said tool a said backsheet made of brittle material, b) in a further die casting step, forming a second layer of foamable material on said first layer such that said second layer substantially embeds said backsheet of said brittle material, c) completing the consolidation of said layers by gelling at elevated temperature and foaming said second layer, d) cooling said tool and removing from said tool the finished article thus produced containing said brittle backsheet in an embedded form. 6. The method of claim 1, wherein a) forming a first layer of material forming the upper layer of the finished product in the die casting tool, b) further forming a second layer of foaming material on said first layer, b ') introducing into said tool cavity, in a predetermined position, said backsheet made of a brittle material, suitably treated with an adhesive such as heat-activated adhesive, to said second layer placing, c) completing the gelling of said layers and foaming of said second layer by gelling at elevated temperature, such as in a heat treatment cabinet, which will adhere to the appropriate surface of the backsheet, d) cooling said tool and removing from said tool a finished article so formed containing said brittle backsheet in an embedded form. The method of claim 1, further comprising the steps of: a) forming a first layer of material forming the upper layer of the finished product in a die casting tool, b) forming a second layer of foaming material on said first layer in an additional die casting step, c) completing the consolidation of said layers by gelling at elevated temperature and foaming said second layer, d) placing the brittle backsheet, which thus forms the surface of the still hot foamed layer, and glues it to said backsheet using appropriate adhesives, e) cooling the finished product and removing it from the tool. Apparatus for carrying out a method according to one or more of the preceding claims, characterized in that it comprises a tool casting tool (2) and a possibly thermostatic counter-tool (8) having the outline of said brittle I reproduce the shape of the backsheet (7) made of a material 1 so that said counter-tool (8) reproduces the shape of said second foamed material facing it. A counter tool for the apparatus according to claim 8, characterized in that it is provided with a separating surface. Counter-tool for the device according to claim 8, characterized in that it is movable. Counter-tool for the device according to claim 8, characterized in that it is provided with one or more parts which can be actuated by mechanical or pneumatic actuators.